The effects of UV-C radiation on the germination rate and fungal contamination of tall fescue seeds were investigated. Samples from the same seed lot were irradiated in two different ways in two consecutive years. The seeds were irradiated with a Hg vapour lamp using different doses. In the first trial one side of the seeds was irradiated, while in the second trial a mirror was used to irradiate the whole seed surface. The results showed that various doses of UV-C irradiation had an effect on the germination rate, but there were no significant differences in germination percentage between the treatments. Differences in fungal contamination rates were observed when the seeds were irradiated on all sides. The presence of 21 fungal genera was identified on the seeds, the saprotrophic fungi
Authors:R. Kiss, J. Sonkoly, P. Török, B. Tóthmérész, B. Deák, K. Tóth, K. Lukács, L. Godó, A. Kelemen, T. Miglécz, Sz. Radócz, E. Tóth, N. Balogh, and O. Valkó
Covell , S. , Ellis , R. H. , Roberts , E. H. and Summerfield , R. J. ( 1986 ): The influence of temperature on seed germinationrate in grain legumes: I. A comparison of chickpea, lentil, soybean and cowpea at constant temperatures . – J. Exp
Authors:Fruzsina Bakti, Anita Király, Erzsébet Orosz, Márton Miskei, Tamás Emri, Éva Leiter, and István Pócsi
Determination of germinationrates in submerged liquid cultures
To determine germinationrates, 10 8 freshly grown conidia were inoculated into 100 ml MNM without any nutritional supplements, or supplemented with 10 mmol l −1 GSH or the mixture of 20
Authors:S. Aboling, M. Sternberg, A. Perevolotsky, and J. Kigel
The relationship between the soil seed bank at the onset of the growing season and the structure of the ensuing vegetation under grazing was investigated in an eastern Mediterranean grassland. Species responses to two contrasting cattle grazing regimes were studied through plant trait analyses. Traits included plant size, phenology, seed size and germination fraction. Changes in species composition of the soil seed bank and the vegetation were analyzed using a plant functional group approach. The results showed that seed bank and relative cover of tall annual and perennial grasses increased when grazed late in the growing season. The opposite was noted for short annual grasses, annual legumes, annual thistles, annual crucifers and other annual forbs. Grazing treatments little affected plant cover of herbaceous perennials. Tall annual and tall perennial grasses have large seeds and germination rates over 90%. Short annual grasses showed similarly high germination rates but with smaller seeds. Annual legumes were characterized by medium size seeds and lower germination fractions (<50%). Tall annual grasses showed high competition capabilities at late grazed paddocks due to a combination of regeneration traits that included: high germination fraction, larger seed and seedling size, and inflorescence with morphological defenses. It is proposed that in addition to plant size and palatability, regeneration traits such as seed dormancy, seed and seedling size play an important role in determining the vegetation structure under different grazing regimes, thus contributing to the high plant species diversity characteristic to Mediterranean grasslands.
Pathogenic variation was studied in 16 fungal isolates of four Fusarium head blight (FHB) species on two modern Syrian bread and durum wheat cultivars using an in vitro Petri-dish test. Three aggressiveness criteria: germination rate reduction, standardized area under disease progress curve (AUDPCstandard), and coleoptile length reduction were evaluated. Regarding AUDPCstandard, intra- and inter-species variability in aggressiveness was detected. The other two aggressiveness criteria did not distinguish fungal isolates within and among species. It seems that AUDPCstandard may be used to measure aggressiveness of FHB on wheat at early stages. The three aggressiveness parameters were not significantly correlated. Cultivar-specific aggressiveness has not been detected. It was not possible to cluster the isolates based on their species origins because of similarity in pathogenic level among the 16 fungal isolates. Bread wheat was more resistant to FHB infection than durum wheat in vitro. The two tested modern cultivars were shown to exhibit moderate to high FHB resistance levels.
The interaction between bread wheat (Triticum aestivum L.) plants and four filamentous species of the Fusarium genus (the causal agent of Fusarium head blight, FHB) was analyzed in an in vitro Petri-dish assay. Pathogenicity criteria as well as germination rate reduction, standardized area under disease progress curve (AUDPCstandard), and coleoptile length reduction were investigated in seeds and six-day-old seedlings showing a moderately level of quantitative resistance, after inoculations with 16 FHB isolates. AUDPCstandard did differentiate FHB isolates and the other two pathogenicity criteria did not. It was not possible to cluster the isolates based on their species origins because of similarity in pathogenic level among the 16 fungal isolates. Cultivar-specific pathogenicity has been detected. The values of disease incidence and disease severity involved in previous artificial head and floret inoculations showed significant correlation with AUDPCstandard: r=0.653** and r=0.559*, respectively. AUDPCstandard could be of potential use in evaluating the pathogenicity of FHB in adult wheat plants.
Germinated brown rice received great attention as healthy ingredient and can be used as an alternative source in the malting and brewing industry. The germination capacity, physico-nutritional properties, sugars, and diastase enzyme activity of brown rice affected by germination times and temperature were determined and compared with control. Soaking in water increased the moisture content of brown rice. Germination rate of brown rice was also increased by higher germination time and temperature and reached maximum after 48 h of germination at 35 ºC. However, dry matter loss, grain weight, and density are affected to a lesser extent. Germination significantly (P<0.05) affects the crude protein, fat, fibre, and ash contents. Total carbohydrates content showed linear relationship with germination time and temperature. During germination, hydrolytic enzymes act on starch, reducing its concentration and resulting in higher total and reducing sugars amounts. Increase in germination time and temperature also increased diastase enzyme activity.
Aggressiveness variation among 16 isolates of four Fusarium species (F. culmorum, F. solani, F. verticillioides and F. equiseti) causing Fusarium head blight (FHB) was studied in vitro. Evaluation of three aggressiveness criteria involved in a Petri-dish test: germination rate reduction, standardized area under disease progress curve (AUDPCstandard), and coleoptile length reduction was carried out on the barley cultivar Arabi Aswad. Results showed differences between barley plants inoculated with FHB isolates and control for the three tested aggressiveness criteria. Regarding AUDPCstandard and Petri-dish aggressiveness index which is calculated from the mean value of three aggressiveness criteria, within and among variation was detected. Intra- and inter-species variability was not distinguished for the other two aggressiveness criteria. However, pathogenic level observed among 16 isolates can not be differentiated within the four FHB species. Significant correlation was detected only between AUDPCstandard and Petri-dish aggressiveness index. The results were comparable with those previously obtained using the same fungal isolates on wheat cultivar in vitro. It seems that FHB isolates recovered from wheat spikes and tested on wheat plants showed a similar range of aggressiveness on a barley cultivar, Arabi Aswad.
Seed samples of four Egyptian broad bean cultivars were tested for seed-borne fungi. The deep freezing method was used to isolate twelve seed-borne fungi viz., Alternaria alternata, Aspergillus flavus, A. niger, Botrytis fabae, Cladosporium cladosporioides, Fusarium oxysporum, F. solani,, Penicillium italicum, Rhizoctonia solani, Rhizopus stolonifer, Stemphylium globuliferum and Trichothecium roseum from the broad bean cultivars viz., Giza 3, Giza 429, Giza 843 and Misr 1. Aspergillus flavus, Botrytis fabae, Fusarium oxysporum and Penicillium italicum were the most predominant fungal species. Aqueous extracts from five wild medicinal plants (Asclepias sinaica, Farsetia aegyptia, Hypericum sinaicum, Phagnalon sinaicum, and Salvia aegyptiaca) which were collected from the Sinai Peninsula, Egypt were tested against the predominant fungal pathogens. All the aqueous plant extracts significantly inhibited the mycelial growth of these fungi, but the extract of Asclepias sinaica exhibited the strongest antifungal activity. The maximum seed germination rate was observed in infested Giza 843 and minimum in Misr 1. Treating seeds with plant extract of Asclepias sinaica (10%) enhanced the percentage of seed germination of all cultivars in both laboratory and pot experiments. Maximum root and shoot lengths of seedlings were recorded in Giza 843 during fungal infestation or treatment by plant extract. In greenhouse experiment, the aqueous A. sinaica extract reduced disease severity and total pigments but increased total phenolics and fruit yield.
Salinity reduces plant growth and yield by affecting morphological and physiological processes. To alleviate the harmful effects of salt stress various approaches involving plant hormones are used. In this study several parameters involving the measurement of cell membrane injury were used to observe whether stress tolerance could be enhanced in Chinese cabbage (B. oleracea capitata L. Chinensis group) by soaking the seeds for 10 h in distilled water (control), or in 100, 150 or 200 mg l−1 gibberellic acid (GA3). The NaCl concentrations were 0 (control), 50, 100 and 150 mM. Seed treated with GA3 showed increased water uptake and decreased electrolyte leakage as compared to that of distilled water-primed seeds even 24 h after soaking under control conditions. Seed priming with GA3 increased the final germination and the germination rate (1/t50, where t50 is the time to 50% germination) under salt stress conditions. Seed priming also alleviated the harmful effect of salt stress on cabbage in terms of fresh and dry weights. Leaf area was higher in plants raised from seeds primed with the higher GA3 concentrations as compared with those raised from seeds treated with distilled water under control conditions (without NaCl) or at 50 mM NaCl stress. The chlorophyll content increased with the NaCl concentration, especially in plants grown from seeds primed with GA3. Plants grown from GA3-primed seeds also suffered lower cellular injury both under control conditions and under NaCl stress.